ANSDIMAT

# Parameter calculation

"Parameter calculation" tabbed dialog is a kind of small calculator for aquifer parameters. Such ones as leakage factor, hydraulic diffusivity, transmissivity, retardation coefficient (for pumping near river) and piezometer shape factor can be calculated here. The latter parameter is used not only for calculations but also for defining the piezometer position that will be then important for some solutions taking into account storage capacity of the piezometer (see Moench’s solutions for confined and unconfined aquifer).

Leakage factor

Leakage factor calculation dialog.

Equations for leakage factor calculation:

 one aqiutard two aqiutards – double prime relates to the parameters of the second aquitard

Hydraulic diffusivity

Hydraulic diffusivity calculation dialog.

Equation for calculating hydraulic diffusivity:

storage coefficient:

In this dialog parameters are automatically inter-calculated.

Retardation coefficient

Retardation coefficient calculation dialog.

Equation for retardation coefficient calculation (in Shestakov’s solution):

Equation for retardation coefficient calculation (in Hantush’s solution):

Where T - aquifer transmissivity, m2/day; k - aquifer hydraulic conductivity, m/day; k' - hydraulic conductivity of the river bed, m/day; m' - river bed thickness, m; b - river width, m.

Shape factor

Shape factor calculation dialog.

This tab allows to choose the piezometer configuration necessary for solutions accounting for piezometer storage capacity (see Moench’s solutions for confined and unconfined aquifer with account for both piezometer and pumping well storage capacity). Furthermore, the user can estimate the shape factor value at given well radius, screen length, aquifer thickness (or initial water saturated thickness of unconfined aquifer), anisotropy and piezometer configuration.

"Modified" option calculates the shape factor used in Moench’s solution: shape factor divided by 2π